Over a period of four years 352 patients suspected of having a carcinoma of the prostate were investigated and 463 cytological and 343 histological examinations were undertaken. In 340 cases the cytological findings on transrectal aspiration biopsy according to Franzen [14] were compared with the histological findings on transperineal punch biopsy. This comparison showed an accuracy of 64.5% and if the PAP III findings were included, of 76.6% in diagnosing prostatic carcinoma by the cytological method. Since the majority of cases were first biopsies and a repeat biopsy was not made in view of the positive punch findings, the chances of detecting a carcinoma of the prostate by aspiration biopsy alone theoretically increase to almost 90%. The reasons for failures in concurrence of findings by the two methods are discussed.